EP3118507B1 - Method for producing a feed pipe for transporting solid materials - Google Patents

Description

The present invention relates to a method for producing a conveying tube for the transport of solids according to the features in the preamble of patent claim 1.

From the prior art it is known to use pipes for conveying solids. For this purpose, various delivery pipes are connected via fittings and pipe bends to promote solids, such as sludge, concrete but also gravel or other solids, using a fluid. The pipes and pipe bends are subject to high wear during the conveyance of solids, so that in particular hardened pipes are used. In this case, it has proved advantageous in the prior art to use double-layered tubes in which an inner tube used made of a hardened steel alloy is used enveloped with an outer tube with rather ductile material properties. In order to create now pipelines, these elongated tubular body are provided at their ends with a pipe collar to connect them in turn with a fitting or a pipe bend and another elongate conveying pipe. The transition point of hardened inner tube However, the delivery pipe to the pipe collar is always a potential vulnerability, which is also exposed to higher wear.

The pipe collar is thereby coupled to the end of the conveyor tube in various ways. For example, the pipe collar can be glued, pressed, screwed or welded to the end of the conveyor pipe.

From the DE 42 02 079 A1 For example, an exhaust pipe for an internal combustion engine of a motor vehicle is known. In order to allow a sliding seat a bell-like expansion with membrane parts is provided.

A solids conveying pipe is further from the DE 40 10 555 C1 known.

From the EP 2 784 366 A1 is a method for producing a conveying pipe for the transport of solids, comprising a double-layered tubular body with hardened inner tube, with an outer tube and with an end-side tube collar known. Object of the present invention is to provide a method to couple a conveyor pipe for a solids transport with a pipe collar, the coupling production-safe with high strength is possible, but at the same time requires a short production time and is economical.

The procedural part of the object is achieved by a method for producing a conveying tube for the transport of solids in patent claim 1.

Advantageous embodiments of the present invention are described in the dependent claims.

• Bereitstellen eines doppellagigen Rohrkörpers mit einem gehärteten Innenrohr und einem dieses umfassende Außenrohr,
• Optionales Erwärmen des Endes des Außenrohres,
• Aufbringen einer stirnseitigen Druckkraft auf das Außenrohr, so dass sich in einem Abstand zum stirnseitigen Ende des Außenrohres ein Längenabschnitt des Außerohres radial nach außen zu einer Ringwulst aufweitet und ein Trennspalt zwischen Außenrohr und Innenrohr ausgebildet wird,
• Aufsetzen eines Rohrbundes und thermisches Fügen des Rohrbundes mit dem Außenrohr durch eine außen umlaufende thermische Fügenaht im Bereich des Ringwulstes.

The inventive method for producing a conveying pipe for the solids transport, wherein the conveying tube has a double-layered tubular body with a hardened inner tube and with a pipe collar coupled to at least one end, is characterized by the following method steps:

• Providing a double-layered tubular body with a hardened inner tube and an outer tube comprising this
• Optional heating of the end of the outer tube,
• Applying an end-side pressure force on the outer tube, so that at a distance from the front end of the outer tube, a longitudinal portion of the outer ear radially outwardly to a torus widens and a separation gap between outer tube and inner tube is formed,
• Placing a pipe collar and thermal joining of the pipe collar with the outer tube by an external circumferential thermal seam in the region of the annular bead.

According to the invention, it is provided that a circumferential annular bead is formed. The annular bead is characterized by a radial outward expansion of the outer tube. Thus, according to the invention, not the entire end is widened, but at a distance from the free end, an axial longitudinal section. The circumferential annular bead can thus also be referred to as a fold in the outer tube. Between the inner circumferential surface or inner surface of the annular bead and the outer circumferential surface of the inner tube thus a separating gap is formed, in which in particular is air. This makes it possible, according to the invention, for the peripheral waist seam to be welded, without the heat-affected zone which arises thereby having an adverse effect on the material structure of the hardened inner tube.

So that now the annular bead is applied, the invention provides that the double-layered tubular body is provided and by applying a compressive force in the axial direction on the end of the tubular body, in particular of the outer tube, the annular bead is formed.

In the simplest embodiment variant, this is done by a sufficiently high compressive force, using an optional outer contour tool.

In a preferred embodiment variant, a predetermined deformation point can furthermore be provided on the outer tube, for example in the form of a circumferential groove in the outer tube. The groove may be formed on the outer circumferential surface or on the inner circumferential surface of the outer tube or on both surfaces outside circumferentially. When applying the compressive force in the axial direction is thus due to the Solldeformationsstelle the length section and thus the emergence of the annular bead determined.

In a preferred embodiment variant, however, the method according to the invention is carried out in such a way that the end of the tubular body, in particular exclusively the longitudinal section at which the annular bead is to be formed, is heated beforehand. The heating is carried out in particular with a circulating inductor or an inductor coil. Heating offers two advantages. On the one hand, the material structure of the outer tube becomes more easily deformable due to the effect of heat. On the other hand, there is already a radial expansion in the heated area due to the thermal heating. So that the inner tube does not undergo structural change as a result of this heating, an internal cooling tool is preferably provided, for example an internal cooling shower.

After the annular bead has been formed, the tube bundle is then coupled or pushed and thermally bonded to the outer lateral surface of the outer tube with a circumferential joining seam, also referred to as a thermal joining seam. Upon cooling of the thermal joining seam, the area of the annular bead can again deform due to radial contraction. In particular, the inner surface of the annular bead can thus in turn come into positive contact with the outer circumferential surface of the inner tube. For the actual welding process, however, the annular bead is radially expanded, so that there is a physical decoupling of the inner circumferential surface of the outer tube and outer lateral surface of the inner tube and takes place due to the thermal joining of the thermal joining seam.

In particular, the heating at 250 ° C to 1500 ° C, preferably at 750 ° C to 1500 ° C and most preferably carried out at 750 ° C to 1000 ° C, wherein preferably only the axial length portion is heated to form the annular bead. Particularly preferably, an outer tube is used with a steel alloy having a carbon content of 0.05 to 0.35 wt%. It is thus in particular a steel alloy, which is conditionally curable. When heated to one of the abovementioned temperatures, structural transformation takes place, in particular into the austenitic microstructure transformation stage. This then brings the radially outward expansion with it. If now the thermal joining seam is to be applied in a direct subsequent process, this can be carried out after the expansion without intermediate treatment. However, should be stored first after the expansion of the tubular body, the expanded outer end of the outer tube are transferred by quenching in an Zwischenstufengefüge and / or martensitic microstructure conversion stage, so that the expanded state is maintained.

The thermal joint seam is then positioned according to the invention relative to the axial direction of the tubular body such that the separating gap is formed in the radial direction inwardly between the inner tube and the outer tube. In particular, the thermal joining seam is performed by a welding process, for example electron beam welding or MIG / MAG welding or TIG welding. However, it is also conceivable that the thermal joining seam is applied by soldering. In particular, in a welding process, the thermal joint seam can also be referred to as collar weld.

In the case of the inventive use of an outer contour tool can be defined by placement of the outer contour tool in the axial direction of the longitudinal section in which the annular bead is formed as a result of applying a directed in the axial direction of compressive force.

The application of the pressure force itself can be carried out with a pressure tool, so that after forming the annular bead, the pressure tool is again removed. However, the application of the pressure force can also be applied by placing the pipe collar and thus on the pipe collar itself on the outer tube. As a result, after forming the annular bead, the pipe collar can remain directly in place and the thermal joining take place.

In this case, it can be dispensed with a use of an outer contour tool, since in particular the pipe collar takes over the function of the outer contour tool. Particularly preferably, an inwardly directed extension of the pipe collar is present, so that when pressing the pipe collar targeted a compressive force is transmitted only to the end face of the outer tube.

However, in the context of the invention, initially only a part of the tubular collar can be placed, which then assumes the function of an outer contour tool and / or a corresponding spacer tool. After this Widening of the annular bead can then be placed on the remaining part of the pipe collar and thermally joined with the annular bead.

Preferably, the pipe collar itself is also double-layered having formed an outer ring or outer collar and inner ring.

The present application further relates to a conveying pipe for the transport of solids, which has a double-layered pipe body with a pipe collar coupled at the end, wherein the pipe collar is peripherally coupled to the outer pipe of the pipe body with a thermal joining seam and wherein the outer pipe radially in a radial direction under the thermal joining seam circumferentially with the formation of a separation gap is widened to the inner tube with a torus. The thermal joint seam is executed in the area of the annular bead.

The conveying tube can be produced in particular by the method according to the invention described above. By the annular bead and the associated separating gap, the thermal effect on the particular hardened inner tube is prevented when applying the thermal joining seam on the outer circumferential surface of the outer tube. Thus, the inner tube, in particular the material structure of the hardened inner tube, can not be adversely affected by the heat-affected zone of the thermal joining seam.

Figur 1

ein erfindungsgemäßes Herstellungsverfahren eines Förderrohres,

Figur 2

eine Teilansicht gemäß Figur 1,

Figur 3

das erfindungsgemäß hergestellte Förderrohr nach Abschluss des Herstellungsverfahrens und

Figur 4

die Teilansicht von Figur 3.

Further advantages, features, characteristics and aspects of the present invention are the subject of the following description. Preferred embodiments are shown in the schematic figures. These are for easy understanding of the invention. Show it:

FIG. 1

an inventive production method of a delivery pipe,

FIG. 2

a partial view according to FIG. 1 .

FIG. 3

the conveyor tube produced according to the invention after completion of the manufacturing process and

FIG. 4

the partial view of FIG. 3 ,

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

FIG. 1 shows a sectional view during a method according to the invention for producing a conveying tube 18. For this purpose, a double-layered tubular body 1 is formed comprising an inner tube 2, which is hardened, and an outer tube 3 comprising the inner tube 2. An end 4 of the tubular body 1 is formed by an inductor 5 in Heated shape of an induction coil, in particular targeted a defined in the axial direction A length section 6 is heated. The length section 6 is arranged at a distance a from the end face 12, as in FIG FIG. 2 shown. Furthermore, an internal cooling tool 7 is provided, so that the inner tube 2 is not heated during the heating of the longitudinal section 6 and the outer tube 3. Then, a double-layer pipe collar 8 is pushed onto the end 4 in the axial direction A, the pipe collar 8 having an outer collar 9 and an inner ring 10. The inner ring 10 itself has according to detail view of FIG. 2 a in the axial direction A-oriented extension 11, which is radially encircling and comes with further pushing the pipe collar 8 form-fitting manner on the end face 12 in particular of the outer tube 3 to the plant. The tube collar 8 is then at least partially on the outer circumferential surface 19 of the outer tube 3, so that the outer tube 3 does not expand here.

Upon further pressing the pipe collar 8 in the axial direction A, it then comes to a configuration according to the Figures 3 and 4 , The previously heated length portion 6 is widened circumferentially in the radial direction R outside and forms a circumferential annular bead 13. Thus, the inner circumferential surface 14 of the outer tube 3 is decoupled from the outer circumferential surface 15 of the inner tube 2 to form a separating gap 16 in the region of the annular bead 13. A circulating thermal joining seam 17 and its heat-influencing zone acting on the outer tube 3 are thus thermally decoupled from the inner tube 2, so that no heat conduction through the outer tube 3 into the inner tube 2 takes place.

The extension 11 of the inner ring 10 has the end face 12 of the outer tube 3 displaced in the axial direction A relative to the inner tube 2, so that the annular bead 13 is formed. The annular bead 13 thus has a distance a to the free end 4 of the tubular body 1. Thus, after formation of the thermal joining seam 17, the conveying pipe 18 produced according to the invention consisting of tubular body 1 and pipe collar 8 is finished. As in Fig. 3 can be seen, it is also possible that the inductor (5) in the axial direction (A) shifts.

It is not shown in detail that the circumferential annular bead 13 can again contract after cooling in the radial direction R, so that the separating gap 16 is no longer present and the inner surface of the annular bead 13 rests positively on the outer circumferential surface 15 of the inner tube 2.

Reference numerals:

1 -

pipe body

2 -

inner tube

3 -

outer tube

4 -

End to 1

5 -

inductor

6 -

longitudinal section

7 -

Internal cooling tool

8th -

pipe Length

9 -

Outer league to 8

10 -

Inner ring to 8

11 -

Extension to 10

12 -

front

13 -

torus

14 -

Inner lateral surface to 3

15 -

Outer lateral surface to 2

16 -

separating gap

17 -

thermal joint seam

18 -

delivery pipe

19 -

Outer lateral surface to 3

A -

axially

a -

distance

R -

radial direction

Claims (13)

1. Method for producing a conveying pipe (18) for the transport of solids, comprising a double-layered pipe body (1) having a hardened inner pipe (2), and with a pipe collar (8) coupled to at least one end (4), comprising the following method steps:

   - providing a double-layered pipe body (1) having a hardened inner pipe (2) and an outer pipe (3) which encases the inner pipe,

   characterised by the following method steps:

   - optionally heating the end of the outer pipe (3),

   - applying a compressive force on the end face of the outer pipe (3), so that a longitudinal segment (6) of the outer pipe (3) expands radially outwards to form an annular bead (13) at a distance (a) from the end (12) at the end face of the outer pipe (3), and a separating gap (16) is formed between the outer pipe (3) and the inner pipe (2),

   - placing a pipe collar (8) thereon, and thermally joining the pipe collar (8) to the outer pipe (3) by an external, circumferential, thermal joining seam (17) in the region of the annular bead (13).
2. Method according to claim 1, characterised in that the heating is carried out with an inductor (5) and/or that the end of the outer pipe (3) is heated to 250°C to 1500°C, in particular to 750°C to 1500°C, preferably to 750°C to 1000°C.
3. Method according to any of claims 1 to 2, characterised in that only the longitudinal segment (6) is heated to form the annular bead.
4. Method according to any of claims 1 to 3, characterised in that an outer pipe (3) is used which has a steel alloy with a carbon content of 0.05 to 0.35 wt %.
5. Method according to any of claims 1 to 4, characterised in that the thermal joining seam (17) is positioned, with respect to an axial direction (A) of the pipe body (1), in such a manner that the separating gap (16) is formed between the inner pipe (2) and the outer pipe (3) inwardly in the radial direction (R).
6. Method according to any of claims 1 to 5, characterised in that when the compressive force is applied, an outer contour tool is placed on the outer shell surface (19) of the outer pipe (3).
7. Method according to any of claims 1 to 5, characterised in that when the compressive force is applied, at least one first pipe collar part is placed on the outer shell surface (19) of the outer pipe (3).
8. Method according to any of claims 1 to 5, characterised in that when the compressive force is applied, the pipe collar (8) is placed on the outer shell surface (19) of the outer pipe (3).
9. Method according to any of claims 1 to 8, characterised in that the compressive force is applied by a tool and the tool is removed after the shaping of the annular bead (13).
10. Method according to any of claims 1 to 9, characterised in that the outer pipe (3) is quenched after the annular bead (13) has formed.
11. Method according to any of claims 1 to 10, characterised in that the pipe collar is placed on the conveying pipe (18) and the compressive force is applied on the outer pipe (3) via the pipe collar (8).
12. Method according to any of claims 1 to 11, characterised in that the thermal joining seam (17) contracts on cooling, so that the outer pipe (3) comes to lie with its inner shell surface (14) against the outer shell surface (15) of the inner pipe (2) in the region of the annular bead (13).
13. Method according to any of claims 1 to 12, characterised in that a circumferential predetermined deformation point is formed in the outer pipe in the region in which the annular bead (13) is to be formed, and in particular the circumferential predetermined deformation point is formed as a circumferential groove.

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